This invention relates to a plotting apparatus, method and film for recording color images, and deals more particularly with a photoplotting apparatus, method and film utilizing non-visible radiant energy, that is, radiant energy outside the visible wavelength region of the radiant energy spectrum to plot in daylight conditions. Within the scope of the specification, daylight includes natural and artificial illumination at light levels rendering objects visible to the unaided eye.
A method for plotting graphic images in color on a photosensitive surface is described in U.S. Pat. No. 4,249,807 by Webster and Larson, and employs a photoplotting apparatus having an optical exposure head to project a beam of radiant energy having different or changeable color components onto the photosensitive surface of a film. Various emulsion layers defining the photosensitive surface record the color components of the projected beam. Drive motors within the apparatus, or photoplotter, move the spot of radiant energy generated by the beam over the film surface and expose the film in accordance with the color components of the beam.
Typically, color film used in photoplotting includes three emulsion layers for recording the color components of a projected beam. The color of any beam may be defined by various amounts of magenta, cyan, and yellow light, the subtractive primary colors, in the beam, and it is common for each of the three emulsion layers in the film to record a respective one of the three primary colors.
The plotting operation using conventional color film must be performed in a low light-level room to avoid exposure of the emulsion layers by the magneta, cyan and yellow color components of the visible light spectrum. An obvious disadvantage associated with plotting in a low light-level environment is that it is difficult for the operator to see. Additionally, special darkrooms must be provided for the plotting function, and control over ingress and egress to the room must be maintained to prevent inadvertent admission of outside light while a plotting operation is underway. The film must also receive special handling when the darkroom conditions do not prevail.
It is, therefore, a general object of this invention to provide a film for recording color images in a daylight or lighted environment and a method and apparatus for plotting on the film in this environment.